Vehicle cooling systems are used in electrically driven rail vehicles, so-called railcars, for cooling main components such as, for example a power electronics and an electric motor. For this purpose the vehicle cooling system can have a cooling circuit in which a liquid coolant circulates and in which the main components are incorporated in a heat-transmitting manner. In addition, a cooling means is incorporated in this circuit, through which cooling air can flow in order to deliver the heat taken up by the coolant to the cooling air. Furthermore, it is usual to use the waste air of the cooling means for cooling ancillary components of the vehicle such as, for example, choke coils, auxiliary transformers, auxiliary motors and switchgear cabinets.
Known from DE 196 32 053 C2 is a vehicle cooling system which has a cooling means of a cooling circuit for cooling a main component of the vehicle, wherein cooling air can flow through the cooling means. The known cooling system additionally has a supply chamber for supplying cooling air to an inlet side of the cooling means. Furthermore, a fan chamber is provided which is connected to an outlet side of the cooling means, in which a fan is arranged and which has a main outlet for cooling air and an ancillary outlet for cooling air. Whereas the main outlet leads to the surroundings of the vehicle, the ancillary outlet is connected to a waste air channel in which an ancillary component of the vehicle is arranged and which has a waste air outlet for cooling air which also leads to the surroundings of the vehicle.
In order in the event of a failure of the fan to be able to nevertheless ensure a sufficient cooling for the respective main component and in particular for the respective ancillary component, it is fundamentally possible to design the vehicle cooling system to be redundant with respect to the fan so that at least two fans are provided. In this case, it can be expedient to arrange the two fans in separate fan chambers which are each connected to the outlet side of the cooling means but have separate main outlets. The two fan chambers are then connected via separate ancillary outlets to the waste air channel. With the aid of a control device, it is then fundamentally possible to open both ancillary outlets for normal operation so that both fans convey cooling air on the one hand to the respective main outlet and on the other hand through the waste air channel to the respective ancillary component and through the waste air outlet. If one of the fans now fails, in an emergency operation with the aid of the control device, the ancillary outlet assigned to the switched-off fan can now be closed so that the remaining switched-on fan conveys cooling air on the one hand through the appurtenant main outlet and on the other hand through the appurtenant ancillary outlet and through the waste air channel to the respective ancillary component and through the waste air outlet. A problem with such a configuration is the fact that the division of the cooling air conveyed by the respective fan to the appurtenant main outlet on the one hand and to the appurtenant opened ancillary outlet on the other hand is only controlled by the different flow resistances. In order to now be able to convey sufficient cooling air through the significantly longer flow path from the respective fan through the appurtenant ancillary outlet, through the waste air channel in which flow takes place through and/or around the respective ancillary component, and through the waste air outlet, the cross-section of the appurtenant main outlet through which flow can take place must have correspondingly small dimension in order to produce a corresponding counter-pressure here. As a result, however the quantity of air flowing through the cooling means is ultimately reduced which reduces the cooling capacity of the cooling means or the appurtenant cooling circuit.